Upon calving, dairy cows begin to produce large quantities of milk, leading to heavy drains upon serum calcium levels. Very low serum calcium levels can cause death of dairy cows within hours or days of calving, and this condition is referred to as "milk fever". Approximately one-fifth of dairy cows suffer milk fever to some extent upon calving, and with jersey cows, this fraction is closer to four-fifths.
Serum calcium commonly is provided by calcium-containing foods. Calcium is stored in the bones of cows, and the bones commonly supply calcium to replenish badly depleted levels of serum calcium. The ease with which calcium stored in the bones passes into the blood serum, and vice versa, appears to decrease with the age of the cows and also appears to be particularly poor in jersey cows.
A number of methods have been proposed in an attempt to reduce the incidence of milk fever in cows. Gerloff, et al., "Dry Cow Feeding and Metabolic Problems", 46th Minnesota Nutritional Conference and Monsanto Technical Symposium, September 16-18, 1985 suggests that excessive calcium and phosphorus intake should be avoided prior to calving in an effort to prevent "PP" (parturient paresis, a synonym for milk fever). The authors state that, "Very low calcium intakes (&lt;20 g daily) are effective in preventing PP and may be fed for the last two weeks prepartum." A summary of procedures for combatting milk fever are discussed in Jorgensen, N. A., "Combatting Milk Fever", Journal of Dairy Science, Vol. 57, No. 8, 1973, pp. 933-944. Methods of combating milk fever included feeding prepartal diets low in calcium, adjusting the dietary calcium-to-phosphorus ratio, feeding acidic diets, mineral acids, or ammonium chloride prepartum, short term administration of 90 to 100 g. of calcium chloride daily, feeding massive doses of vitamin D prepartum, and prepartum administration of 25-hydroxycholecalciferol. The intravenous administration of calcium salts is recommended as a treatment for severe milk fever, and is reported in Howard, Ed., "Current Veterinary Therapy I: Food Animal Practice", W. B. Saunders Co., Philadelphia, 1981, pp. 340-343. This text mentions the administration of vitamin D2 and of a vitamin D3 metabolite ante partum to reduce the incidence of milk fever. Also mentioned is the administration of 90 to 100 grams of calcium chloride orally for two to three days ante partum to two to three days postpartum to reduce incidence of the disease.
Notwithstanding the treatments suggested above, milk fever remains an extremely serious disease that affects postpartum dairy cows. A simple, safe and effective procedure for avoiding the onset of severe milk fever is much to be desired.